In the liquid crystal display field, normal display of liquid crystal display pictures depends on refraction of light caused by deflection of liquid crystal molecules. In the process of manufacturing a liquid crystal display, liquid crystal molecules need to be arranged in certain directions and angles, namely the liquid crystal molecules need to be aligned. Liquid crystal alignment technologies include a rubbing alignment technology and a non-rubbing alignment technology.
The rubbing alignment process means that a rubbing roller rubs the surface of an alignment film in a certain direction, thus forming grooves for arranging liquid crystal molecules in certain directions and angles. The rubbing roller includes a roll shaft and rubbing cloth attached to the roll shaft. During rubbing, the rubbing cloth directly rubs the alignment film, so the surface condition of the rubbing cloth directly influences the quality of alignment. Generally, the rubbing cloth adopts nylon cloth, fibers or cotton cloth. Then the quality, the weaving technique and the like of the rubbing cloth may directly influence the quality of the rubbing process.
The rubbing cloth is adhered to the rubbing roller by a double-faced adhesive tape. If the rubbing cloth itself is not uniform in thickness or has badness when winding on the roll shaft, e.g. surface protrusion, dust adhered to surface and the like, it may scratch the surface of the alignment film during alignment to influence the quality of pictures.
Thus, before the rubbing cloth is used for alignment, unqualified rubbing cloth should be removed.
Moreover, a large amount of static charges may be generated during the rubbing process and accumulated on the surface of the rubbing cloth. The static charges accumulated on the surface of the rubbing cloth may attract alignment film chips generated in the rubbing process, so that the surface condition of the rubbing cloth is degraded; at cloth slits, the tail end of the rubbing cloth may rise, drop off or the like during rubbing, and these greatly increase the risk of alignment badness.
At present, the rubbing cloth is mainly detected by experiential observation of operators, and the surface condition thereof is judged by experience.
On the other hand, quantum dots are nanoparticles formed by a semiconductor material, and have many unique characteristics due to the size effect thereof. One of the important characteristics is fluorescent effect. The quantum dots emit fluorescence under the irradiation of an excitation light source. The quantum dots is adjustable in color, and have narrow emission spectrum, high photochemical stability and long fluorescence lifetime, and the emission spectrum of the quantum dots can be controlled by changing the size of the quantum dots.